Our Universe - 1 Class 3 Worksheet SST

Q1: Multiple Choice Questions (MCQs)

(i) Name the planet closest to the Sun.
(a) Mercury
(b) Earth
(c) Venus
(d) None of them
Ans: (a)
The eight planets are Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune. Mercury is closest to the Sun. Neptune is the farthest. The smallest planet in our solar system and nearest to the Sun, Mercury is only slightly larger than Earth's Moon.

Solar System(ii) Many years ago, a huge ball of fire was created. This theory is known as
(a) Big Bang
(b) Solar system
(c) Earthquake
(d) None of these
Ans: (a)
During the Big Bang, all of the space, time, matter, and energy in the Universe was created. This giant explosion threw matter in all directions and caused space itself to expand. As the universe cooled, the material in it combined to form galaxies, stars, and planets. The big bang is how astronomers explain the way the universe began. It is the idea that the universe began as just a single point, then expanded and stretched to grow as large as it is right now—and it is still stretching!

Big Bang(iii) What is the name of the earth’s galaxy?
(a) Milky Way
(b) Comets
(c) Orbit
(d) None of them
Ans: (a)
Our Sun and all the planets around it are part of a galaxy known as the Milky Way Galaxy.  Earth is in the galaxy called Milky Way Galaxy. The Milky Way is a large spiral galaxy. Earth is located in one of the spiral arms of the Milky Way.

Milky Way Galaxy(iv) What does the Big Bang theory propose about the origin of the universe?
(a) The universe is eternal and unchanging
(b) The universe began with a huge explosion
(c) The universe was created by a powerful deity
(d) The universe is a result of continuous expansion
Ans: (b)
The Big Bang theory suggests that the universe originated from a massive explosion.

(v) Which galaxy is the home of our planet Earth and the Solar System?
(a) Andromeda galaxy
(b) Milky Way galaxy
(c) Solaris galaxy
(d) Orion galaxy
Ans: (b)
Earth and the Solar System are part of the Milky Way galaxy.

Q2: Match the following

Ans: 
1. Sun - (d)
2. Earth - (c)
3. Moon - (a)
4. Milky way - (b)

Q3: Fill in the blanks

(i) _________ is the fourth nearest planet to the Sun.
(ii) While the planet revolves, it also rotates on its __________.
(iii) The universe contains thousands of ____________.
(iv) We live on the planet _____________.
(v) The Milky Way galaxy contains approximately __________ billion stars.
Ans:
(i) Mars
(ii) axis.
(iii) Stars.
(iv) Earth.
(v) 200

Q4: True and False

(i) There are billions of galaxies in the universe.
(ii) The Earth is the third planet in the solar system.
(iii) The moon is an artificial satellite of the earth.
(iv) Satellites, like the Moon, do not rotate on their respective axes.
(v) The Sun is a planet in our Solar System.
Ans:
(i) True
While estimates among different experts vary, an acceptable range is between 100 billion and 200 billion galaxies in the universe.
(ii) True
Our solar system has eight planets. Earth is the third planet from the sun. Mercury is the first because it is closest to the sun. Venus is second.
(iii) True
A satellite is a body that revolves around another body in a path called the orbit. The earth is a satellite of the sun because it moves around the sun and the moon is a satellite of earth because it moves around the earth. Satellites that are put into orbit by man are called artificial satellites.

Moon - Artificial Satellite of Earth(iv) False
Satellites, including the Moon, rotate on their respective axes.
(v) False
The Sun is a star and is at the center of our Solar System.

Q5: Answer the following Questions

(i) How many stars are there in the earth’s galaxy?
Ans: It is estimated that the galaxy contains 100–400 billion stars and at least that number of planets.
It’s impossible to know how many stars exist, but astronomers estimate that in our Milky Way galaxy alone, there are about 300 billion.

(ii) What is Milky Way?
Ans: The Milky Way is the galaxy in which we live. It is a spiral shaped galaxy that contains several hundred billion stars, including our Sun. It is about 100,000 light-years across and about 10,000 light-years thick.
Milky Way Galaxy(iii) Describe the Big Bang theory.
Ans: The big bang is how astronomers explain the way the universe began. During the Big Bang, all of the space, time, matter, and energy in the Universe was created. This giant explosion hurled matter in all directions and caused space itself to expand. As the universe cooled, the material in it combined to form galaxies, stars, and planets.

(iv) What do you mean by the solar system?
Ans: Our solar system is home to Earth and seven other planets. Each planet rotates on its own axis while revolving around the Sun. The term Solar System refers to the "family" of the Sun. The Sun is a star around which eight planets, among other celestial objects, revolve in orbits. This whole system of bodies is called the Solar System. The Sun is the "head" of this system.